新建跨河橋梁對河川洪水位之影響研究：以新鹿寮鐵路橋為例

由於新建跨河橋梁大多必須於河道中設置橋墩，故對河川洪水位的影響是不可避免的。本研究藉由數值模擬分析方法，以新建新鹿寮鐵路橋橋墩布置方案，探討新鹿寮鐵路橋橋墩設置後對鹿寮溪洪水位之影響，分析結果將提供主管機關作為災害整備及應變之參考。本研究使用美國陸軍工程師團所發展之河川二維水理演算數值模式（TABS-2），針對100年重現期鹿寮溪各河段之設計流量，進行新鹿寮鐵路橋橋墩設置方案之水理分析。由二維水理演算數值模式之分析結果顯示，新鹿寮鐵路橋新建工程橋墩設置後，鹿寮溪之洪水位將抬升，與鹿寮溪現況案例相較，鹿寮大橋下游面平均壅高約0.5～0.6 m，而其上游之鹿寮溪第4斷面則平均壅高0.02 m。

關鍵字

新建跨河橋梁；橋墩；河川洪水位； TABS-2 ；災害整備及應變

並列摘要

New-built bridges must inevitably be built across the river reach. Simulation of backwater effect due to new bridge piers is very important for river safety assessment. Therefore, this paper investigates the effect of new-built bridges on upstream river stage by numerical analysis. The presented model is the TABS-2 two-dimensional numerical modeling system developed by US Army Engineering Corps. The model is applied to simulate the 2D flow field and river stage in the upstream and downstream reach of new railway bridge on the Luliao river in Taiwan under 100-year return period flood. The simulated results indicate that the affected river stage ranges from 0.5-0.6 meters in the downstream reach of Luliao Bridge. The results also show that the river stage at the cross-section 4 upstream of Luliao Bridge obtains affected river stage of 0.02 meters. The presented results in this paper provides a helpful guideline for river managers to make decisions associated with disaster preparedness and response.